What were the 2 food-based chemical
reactions we studied in yesterday’s
What are the proteins that speed up metabolic
Collect LAB: Exploring Enzymes
Shape, Function, and Naming
Factor’s that slow enzymes
ENZYMES & SUBSTRATES
Enzymes are proteins that catalyze (speed
up) chemical reactions in the body
The molecules that are affected by enzymes
are called substrates
Example: Amylase is an enzyme in saliva
that breaks down starchy foods like bread
and pasta. In this case, starch is the
substrate of amylase.
SUMMARY OF ENZYME PROPERTIES
Shape: Enzymes are globular (balled up) proteins
Function: Enzymes work by temporarily bonding with
Reusable: A single enzyme can be used multiple times
Name: Enzymes are named for the substrates they
SHAPE OF ENZYMES
Enzymes are long protein chains that are “knotted up”
like a ball of yarn.
The surface of an enzyme has a small pocket called
the active site which is shaped to bind substrate
HOW ENZYMES WORK
Substrate molecules temporarily bond with the
enzyme at the active site.
The enzyme bends the substrate in a way that
either breaks the molecule apart or allows it to
bond with another substrate
Once the reaction is complete the enzyme
releases the products.
SUMMARIZE WHAT IS HAPPENING IN THE VIDEO
CLIP . . .
ENZYMES ARE REUSABLE
An enzyme only bonds with the substrate it
works on for a short time.
After the reaction is over, the enzyme returns
to it’s original shape and is ready to work
A single enzyme can induce millions of
reactions per second.
Enzymes are specific to only one substrate.
Since each enzymes only works on one
reaction, they are named for the molecules they
To name an enzyme, simply add the ~ase
Lactose sugar is broken down by the enzyme
FACTORS THAT SLOW ENZYMES
Enzymes are only effective when their active
site is in the proper shape.
Since enzymes are proteins, they can
become denatured (unfolded) and will no
2 things will denature proteins
Changes in pH
Changes in Temperature
Many chemical reactions need energy to begin.
This energy that starts a reaction is called the
Photosynthesis requires activation energy from the
Wood will not start burning without initial heat
ENZYMES LOWER ACTIVATION ENERGY
Enzymes speed reactions up by reducing the
amount of activation energy a reaction
The activation energy is reduced because
the molecules at the active site are held in
positions that make reactions easier.